This invention relates to granulated solid fuel burners, and more particularly to one which insures more complete combustion of the fuel and prevents flashback in the fuel supplied thereto, which allows efficient burner operation over a wide turndown range, and which provides for control of flue gas temperature exiting the burner.
With the advent of concern for energy conservation, it has become increasingly important to provide combustion devices capable of burning less expensive and more plentiful fuels. One general type of such fuels includes the so-called granulated solid fuels such as ground wood particles, wood shavings and sawdust, and other non-wood granulated substances such as ground rubber, ground bagasse, etc. Such fuels can be difficult to burn but nevertheless can produce hot flue gases which can be used for a variety of applications, including boilers, warm air furnaces, etc. As in all combustion devices, it is important that the combustion process be carried out efficiently for, if not, the burner will generate excessive smoke and soot, and unburned or incompletely burned fuel will remain in the burner further reducing its efficiency or even interrupting its operation.
Furthermore, it is desirable that the burner have a wide turndown range, i.e., that it be capable of operating at a greatly reduced output level during periods of reduced demand or non-demand, and that it resume normal operation quickly when output demand resumes. In addition, burners of the type should be capable of easy startup.
Still further, it is desirable that the temperature of flue gases exiting the burner be controllable.